Underground thermal energy storage utes systems store energy by pumping heat into an underground space there are three typical underground locations in which thermal energy is stored boreholes aquifers and caverns or pits the storage medium typically used for this method of thermal energy storage is water. Underground thermal energy storage utes is a form of energy storage that provides large scale seasonal storage of cold and heat in natural underground sites 3 6 there exist thermal energy supplying systems that use geothermal energy for cooling and heating. In a technology known as underground thermal energy storage utes energy sources charge a subsurface store for use at a later season an example is the use of winters cold to charge a store which will be used in summer to cool a building similarly solar energy can be stored in summer for use in winter. Underground thermal energy storage is well suited to district energy systems where thermal energy is transferred trough piping networks for heating and cooling adding a thermal energy store increases the thermal capacity of district energy systems improves energy efficiency and resiliency and benefits system operators and users